Question

The amount of ripple in the output voltage (V­₀) of a frequency to voltage converter is

1. Directly proportional to value of integrating capacitor (C_in) and the frequency of the input (f_in)
2. Inversely proportional to value of integrating capacitor (C_in) and the frequency of the input (f_in)
3. Independent of value of integrating capacitor (C_in) and also independent of frequency of input (f_in)
4. Independent of the frequency of input (f_in) but directly proportional to the value of integrating capacitor (C_in)

Answer 1

Correct Answer - Option 2 : Inversely proportional to value of integrating capacitor (C_in) and the frequency of the input (f_in)

The output voltage & ripple voltages of basic frequency to voltage converter is given below:

\({V_{out}} = {f_{in}} \times \left[ {\frac{{{R_L}}}{{{R_s}}}} \right] \times \left( {1.9v} \right) \times \left( {1.1\;{R_t} \cdot {C_t}} \right)\)

Output ripple P.P is given by:

\(\frac{1}{{{C_{in}}}} \times \frac{{\left( {1.9\;v} \right) \times \left( {1.1\;{R_t}\;{C_t}} \right)}}{{{R_s}}}\)

Therefore, the amount of ripple in the output voltage of a frequency to voltage converter is independent of the frequency of input (f_in) & inversely proportional to the value of integrating capacitor (C­_in)

If we want a quicker response, it is easy to decrease the value of C_in, but the ripple will increase by the same factor.

Most frequency-to-voltage converters suffer from the classical trade-off ripple versus speed of response.